For the purposes of interpreting the disclosure made herein, the terms “CubeSat deployer”, “satellite deployer”, “satellite deployer system”, or derivations thereof are used interchangeably and should be considered synonymous.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
Aerospace development requires (by its nature) access to space. Due to the difficulties, hazards, and costs inherent in aerospace activities, satellites have been, and will continue to be the primary means for the vast majority of extra-planetary operations. Satellites have been used in aerospace applications to explore space, gather and relay data, perform experiments, and do any other number of tasks for which their creators have designed them.
Picosatellites, including CubeSats, provide a means for minimizing the financial barrier to space entry. A CubeSat is a miniature satellite having a width of 10 cm, a height of 10 cm and a length that may be variable. Common CubeSat dimensions are “1U” (10.0×10.0×13.5 cm), or multipliers thereof, ie. “2U” (10.0×10.0×27.0 cm), and “3U” (10.0×10.0×40.5 cm) 2U×3U (10.0×20.0×40.5 cm), etc. The components used to build CubeSats are usually relatively inexpensive, off-the-shelf, electronics. The small size of these CubeSats and other picosatellites coupled with their uniform dimensions and inexpensive components make these satellites an attractive means of accessing space at a relatively small cost.
Miniaturized satellites can simplify problems commonly associated with mass production, although few satellites of any size, other than “communications constellations” (where dozens of satellites are used to cover the globe), have been mass-produced in practice.
One reason for miniaturizing satellites is to reduce the cost associated with transporting them into space. Heavier satellites require more energy to transport them into orbit or open space, thereby requiring larger rockets with greater fuel requirements, which results in higher costs. In contrast, smaller and lighter satellites require less energy and less volume (requiring smaller and cheaper launch vehicles) and may be launched in multiples, or in other words, deployed in groups and at the same time. These small satellites, such as CubeSats and other picosatellites, can also be launched in a “piggyback” manner, using excess capacity available on already loaded launch vehicles.
The high cost of transporting mass from the surface of a stellar body into an orbit around a celestial body, or open space, has limited the development of aerospace activity. This high cost per unit mass has made minimizing the mass of the objects being sent into space particularly important.
In order to achieve their purpose, CubeSats must be transported out of the atmosphere and released into space (whether that is into an orbit around a celestial body or into open space). Satellite deployers are used to store and protect satellites during their transportation into space. These satellite deployers protect the payloads stored inside of them from damage caused by the inherent stresses resulting from launching such payloads into space. The satellite deployer must also safely and efficiently deploy their satellite payloads into the correct trajectory once the system has reached space.
The standardized specification of CubeSats also allows for the deployment means of these satellites to be standardized as well. The standardization among both payloads and deployers enables quick exchanges of payloads without the need of customized payload-deployer interfaces. It also allows for easy interchangeability of similarly dimensioned satellites.
Associated with the minimization of mass is the minimization of volume. This is important in the field of space transportation since there is a finite amount of usable storage volume inside of space vehicles.
This minimization of mass and volume is important not only for satellites, but for the systems used to store, transport and deploy the satellites.
Satellite deployers may be designed as metal storage containers into which satellites are placed. These container-type satellite deployers usually provide a door at one end, through which payloads may be loaded and unloaded. After loading, the deployer system's door is sealed, and the deployer system is then mounted onto a launch vehicle which is responsible for transporting the deployer system, including any satellites or other space payloads stored therein, into space. Once the system is in space, the deployer may then be taken through an airlock so that the deployer is in contact with space. Once the deployer is in contact with space, the deployer's door is pointed in the desired direction of deployment (away from any potential obstructions, such as other deployer's doors). The door(s) to the deployer system are then opened, and a propulsion means is used to eject the payload(s) into space in a manner conforming to predetermined parameters depending on the payload's intended use.
CubeSat deployers may have a housing that may be tubular in shape with a door which opens to reveal an open end through which the satellites may be ejected. Such satellite deployers have an onboard ejection mechanism with which can be used to supply the energy for ejecting the payloads from the interior volume of the deployer into space. This deployment means may be one or more springs, cold gas, hot gas, compressed gas, or other such energy sources (or a combination thereof) capable of imparting a force onto the space payload such that the payload is forced out of the interior volume of the deployer. The door system is used to contain the payloads during the storage phase until they are ready to be deployed. Generally this type of satellite deployment system may utilize a single door which opens wide, having a door travel path of significantly more than 90 degrees. This type of door mechanism requires a large door travel path to provide sufficient clearance so as to allow for the egress of their space payload(s).
Current deployers can carry a maximum of three 1U CubeSats. Their release mechanism generally consists of a motor with a lead screw mechanism that is used to open the door and allow for release of the payload. The combination of the maximum load and large door mechanism limits the number of CubeSats the can be deployed for a given mission.
On the International Space Station (ISS) the CubeSats and their deployers must at some point pass through the limited volume of the craft's airlock. With this restriction, and based on the dimensions of the ISS' airlock, which is known in the art, at most only six 1U CubeSats may be deployed with current deployer systems in any single airlock cycle on either the ISS itself, or on other space vehicles having similarly configured airlocks. The teachings included in the present disclosure allow for a total of eight satellite deployers loaded with six CubeSats each to pass through an airlock with similar dimensions that of the ISS in a single cycle. This results in the potential for 48 CubeSats deployments in a single airlock cycle.
A limitation of current satellite deployer technology arises as a result of the design of a deployer's openings and the associated large door travel path, or envelope. The satellite deployer's door system may rotate 180 degrees or more about a hinge when transitioning from a closed to an open configuration. A door travel path having a rotation greater than 90 degrees may impede an adjacent door system's ability to open fully and/or may compromise the open end of adjacent satellite deployers by blocking a portion of said open end. This may result in the inability to effectively use multiple satellite deployers when arranged in close proximity to one another, preventing optimal packing of the satellite deployers within the limited interior volume of space vehicles and their airlocks.
Another limitation of current satellite deployers is the lack of redundant lock-disengagement circuits. Due to the risks inherent in space activities, redundant systems are recommended in case of a malfunction, that would otherwise compromise operations.